With the exception of left field, there are no real contests for starting positions for the 2021 Twins. If he doesn't start as the most frequent left fielder, Luis Arraez will get frequent starts in the infield. The major competition for roster positions will come down to backup outfielders, another utility infielder (particularly if Arraez gets a lot of starts in left) and perhaps a third catcher.
I've seen posts suggesting that three rookies, outside of Alex Kirilloff, should get consideration for backup outfielder and utility infielder. That would be Travis Blankenhorn, Nick Gordon and Brent Rooker. The three have a combined total of 25 plate appearances in eight major league games. Rooker is a corner outfielder who played some first base early in his professional career, Blankenhorn has played second, third and left field and Gordon has divided his minor league time between second and shortstop. Ideally, the Twins could use someone to back up at all infield positions and left. In my opinion, none of the rookies here is a fit to be a bench player. None of these guys project as an above average performer in the field.
It seems to me that asking inexperienced players to assume a bench role, starting no more than once or twice a week, is asking a lot. They are not used to the role and with the added pressure of proving they belong, I don't think it is putting a player in a position where he has a reasonable chance to succeed. If there is hope for a player to become a major league regular, I don't think bench roles are a good learning experience.
The non-roster invitees and waiver claim Kyle Garlick would appear to be better fits for backup roles than the rookies who were in the Twins system, even if their upsides are limited. When injuries occur, the rookies would probably get a chance to get some regular playing time and have a more reasonable chance to prove their worth on the biggest stage.